Dr Chris Fenn is a Nutritionist and motivational speaker. This article was written by her for cyclists but has much useful information.

Magnesium is a mineral with important functions for cyclists, but has quietly become one of the most common mineral deficiencies in the UK.

Minerals are pretty tough nutrients: you can boil them or bake them and, unlike vitamins, they will still be there in your bowl of soup when all the cooking is done. But although they aren’t easy to destroy, you do have to eat them in the first place! One of the main reasons for a magnesium deficiency, particularly among athletes, is poor diet.

Magnesium is found in whole grains, nuts and green vegetables. If your eating habits fit into the ‘grab and go’ category and your daily routine is spent snacking due to a hectic work and training schedule, you are likely to rely on over-processed, poor quality carbohydrate foods.

These will refuel your muscles but won’t supply the added extras, the essential nutrients. Not only does the refining process remove a large portion of magnesium and other minerals, but eating these types of foods also increases the requirement for these nutrients. It is no wonder that a deficiency is so common.

Enzyme activity

The main function of magnesium is enzyme activation. Many enzymes which are involved in the process of energy release also have co-factors which rely on magnesium. Not surprisingly, a lack of magnesium shows up as fatigue. This can develop into chronic fatigue syndrome (CFS) where you struggle to have enough energy to get out of bed, let alone get out on your bike.

The highest concentration of magnesium is found in organs which are the most metabolically active (brain, heart, liver and kidney). Even a relatively mild deficiency can affect these tissues. The good news is that after boosting magnesium levels (usually by taking a supplement), your energy levels also quickly improve.

Because of its role in soft tissues and nerves, a lack of magnesium can also be an underlying feature in night-time fidgeting – a condition known as restless legs syndrome. Deficiency interferes with the transmission of nerve and muscle impulses, causing general irritability and nervousness. Other signs and symptoms of magnesium deficiency are mood swings, irritability, mental confusion, muscle weakness and cramps, loss of appetite and insomnia.

Women who suffer from abdominal cramps and pre-menstrual syndrome (PMS) tend to have low levels of red blood cell magnesium. In one study, high doses of magnesium (360mg three times each day) dramatically relieved PMS-related mood changes and cramps.

Magnesium is also essential for the proper functioning of the entire circulatory system. The next time you feel your heart pounding as you sprint uphill on your bike, you know that magnesium is in there helping to make it all happen. Through its critical role in promoting the work of the heart and circulation system, magnesium supplementation is also used in the prevention and treatment of strokes and heart disease.

Magnesium rich foods…

Tiredness, PMT, muscle weakness and cardiovascular problems are common health challenges and there are several factors associated with these. However, a magnesium defiency is one of them and is often overlooked. Modern refining techniques have helped to strip magnesium from the food we eat, but even if you choose whole foods and unprocessed foods many of these do not contain the levels of minerals that they once did.

Over the last 50 years, there has been a general decline in the mineral content of soil and therefore in the cereals and vegetables grown in this depleted soil. The organic system of production helps to feed and nurture the soil so that it contains a higher level of minerals. These then get taken up by the plants so that organic cereals, kale, broccoli and cabbage have a higher mineral content compared with non-organic produce.

Adults need about 300mg magnesium per day. The best sources are brazil nuts, sunflower seeds, cashew nuts, wheatgerm, almonds, raisins and sesame seeds. Green vegetables are also a fairly good source since each molecule of chlorophyll (the pigment which gives the green colour to leaves) contains an atom of magnesium. If you are lacking in energy and suffer regularly from muscle cramps and mood swings, you are likely to benefit from a more regular intake of magnesium.

For a mineral-boosting breakfast, mix chopped mixed nuts into porridge, or add them to unsweetened muesli with raisins and extra wheatgerm.

Liquorice is a good source of magnesium, but choose the original black variety made from molasses rather than brightly coloured Allsorts. Liquorice can provide a dose of fast release carbohydrate and is a useful snack to carry on a ride.

If you decide to take a magnesium supplement, choose the citrate form or magnesium chelated with amino acids. These are twice as well absorbed as magnesium carbonate or sulphate.